This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A primary goal of this collaboration is to determine what physical changes are responsible for differences in scattering exhibited by in vivo dysplastic and non-dysplastic cervical tissue. The use of perturbation Monte Carlo (pMC) methods is critical to understanding the relationship between these physical changes and measured light scattering properties. Use of such methods will not only produce dramatic gains in computational efficiency but also improve the accuracy in model precitions. physical changes lead to the scattering changes we measure in vivo, is to be achieved.